Almost half of the carbon dioxide that humans release into the environment is taken up by the world’s oceans and the terrestrial biosphere. In this manner, greenhouse gases are partially extracted from the atmosphere, which alleviates the process of global warming. But will the land and the seas be able to continue storing carbon dioxide in the future? Researchers aren’t sure. Changes in ocean circulation, woodland clearances and stress reactions in forests could reduce their capacity to act as carbon sinks.